The objective of this research is to expand the size and scope of a child injury data base, developed during Phase I, for use in biomechanics research. The focus of this study is the definition of injuries observed in young children, age 12 and under, who have been involved in automobile accidents while restrained by child restraint systems, adult restraint systems or unrestrained. A four year retrospective study will be performed over a two year period with the aim of correlating the reported injuries of child accident victims, the involved restraint device, the physical properties of the injured child, and the accident characteristics. This study will include injury/police report correlated data from 13 counties in western New York State. This retrospective epidemiologic study will be supplemented with control data of uninjured children involved in motor vehicle accidents in the same counties and over the same time period. The results of this study will lead to increased understanding of child impact injury mechanisms, better definition of child impact tolerance levels, and the development of more effective child restraint systems, child size test dummies possessing higher levels of biofidelity, and more realistic performance evaluation criteria for child protection devices.